From nobody Mon Feb 9 09:38:28 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19983C04A6A for ; Thu, 10 Aug 2023 16:04:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236494AbjHJQEP (ORCPT ); Thu, 10 Aug 2023 12:04:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54784 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235124AbjHJQDx (ORCPT ); Thu, 10 Aug 2023 12:03:53 -0400 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CBD52723 for ; Thu, 10 Aug 2023 09:03:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=P9MEKtJhSMgnLsIUAgMIyHv1PUh5yex761a8f47xbF0=; b=swq6cD3C1dUjaAvuAZM/bLVita EqMOTO6SwjYjNG9oMqWML6wVDB5DJxM3riDflq6oaDk42oPSxPpKzLJeXVyN2Zdv3dnQsGIiBqELS 0lTNLEQPv+gEKg1REF/jWQjjRs/w/PPGTHSaGaSzJni2CulOXRxuR4EAvIcsURC02sShGbGg3krVJ GdE6MagS742FMJ/rBh7uQXLkH4bb9cnHL1GSTLFpNw0rorCbTNzASvn+lIwiY4EhAImkoZuJwVRIb 4sR6vb+3ojeksfecp522nDaLYW0pD5AEzSFvq0PyTWaBRBrjIVx3kVFh18AhEl10RRx4OpqjmX1P8 Gzt1f4hw==; Received: from [38.44.68.151] (helo=killbill.home) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1qU88N-00GjYD-Fv; Thu, 10 Aug 2023 18:03:35 +0200 From: Melissa Wen To: amd-gfx@lists.freedesktop.org, Harry Wentland , Rodrigo Siqueira , sunpeng.li@amd.com, Alex Deucher , dri-devel@lists.freedesktop.org, christian.koenig@amd.com, Xinhui.Pan@amd.com, airlied@gmail.com, daniel@ffwll.ch Cc: Joshua Ashton , Sebastian Wick , Xaver Hugl , Shashank Sharma , Nicholas Kazlauskas , sungjoon.kim@amd.com, Alex Hung , Pekka Paalanen , Simon Ser , kernel-dev@igalia.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 08/34] drm/amd/display: document AMDGPU pre-defined transfer functions Date: Thu, 10 Aug 2023 15:02:48 -0100 Message-Id: <20230810160314.48225-9-mwen@igalia.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230810160314.48225-1-mwen@igalia.com> References: <20230810160314.48225-1-mwen@igalia.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Brief documentation about pre-defined transfer function usage on AMD display driver and standardized EOTFs and inverse EOTFs. Co-developed-by: Harry Wentland Signed-off-by: Harry Wentland Signed-off-by: Melissa Wen --- .../amd/display/amdgpu_dm/amdgpu_dm_color.c | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c b/driv= ers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c index cc2187c0879a..7f13bcdaf016 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c @@ -85,6 +85,45 @@ void amdgpu_dm_init_color_mod(void) } =20 #ifdef AMD_PRIVATE_COLOR +/* Pre-defined Transfer Functions (TF) + * + * AMD driver supports pre-defined mathematical functions for transferring + * between encoded values and optical/linear space. Depending on HW color = caps, + * ROMs and curves built by the AMD color module support these transforms. + * + * The driver-specific color implementation exposes properties for pre-ble= nding + * degamma TF, shaper TF (before 3D LUT), and blend(dpp.ogam) TF and + * post-blending regamma (mpc.ogam) TF. However, only pre-blending degamma + * supports ROM curves. AMD color module uses pre-defined coefficients to = build + * curves for the other blocks. What can be done by each color block is + * described by struct dpp_color_capsand struct mpc_color_caps. + * + * AMD driver-specific color API exposes the following pre-defined transfer + * functions: + * + * - Linear/Unity: linear/identity relationship between pixel value and + * luminance value; + * - Gamma 2.2, Gamma 2.4, Gamma 2.6: pure gamma functions; + * - sRGB: 2.4 gamma with small initial linear section as standardized by = IEC + * 61966-2-1:1999; + * - BT.709 (BT.1886): 2.4 gamma with differences in the dark end of the s= cale. + * Used in HD-TV and standardized by ITU-R BT.1886; + * - PQ (Perceptual Quantizer): used for HDR display, allows luminance ran= ge + * capability of 0 to 10,000 nits; standardized by SMPTE ST 2084. + * + * In the driver-specific API, color block names attached to TF properties + * suggest the intention regarding non-linear encoding pixel's luminance + * values. As some newer encodings don't use gamma curve, we make encoding= and + * decoding explicit by defining an enum list of transfer functions suppor= ted + * in terms of EOTF and inverse EOTF, where: + * + * - EOTF (electro-optical transfer function): is the transfer function to= go + * from the encoded value to an optical (linear) value. De-gamma functio= ns + * traditionally do this. + * - Inverse EOTF (simply the inverse of the EOTF): is usually intended to= go + * from an optical/linear space (which might have been used for blending) + * back to the encoded values. Gamma functions traditionally do this.=20 + */ static const char * const amdgpu_transfer_function_names[] =3D { [AMDGPU_TRANSFER_FUNCTION_DEFAULT] =3D "Default", --=20 2.40.1